Conventionally, the input device provided with capacitive touch sensors are well known (see, for example, Patent Literature 1 below).
The conventional input device has a plurality of capacitive touch sensors arranged in a matrix on the surface thereof. Each capacitive touch sensor includes a rectangular detection electrode and an indication mark printed on a sensor surface at a location directly above the rectangular detection electrode. The capacitive touch sensor detects a finger of a user being very close to or in contact with the indication mark, based on the change in capacitance.